During an episode of his TV show, Professor Membrane explains the dangerous potential ramifications of Time Travel and how anyone who would build a time machine would be a "complete moron." Zoom out to Zim doing just that.
Zim has a new invention- a time portal that will allow him to send objects into the past. He hopes to use this to send a robot back in time to kill Dib in the past. Unfortunately, the robot isn't compatible with the portal, and gets ejected. Zim is furious, grabs a rubber pig that GIR had been playing with, and lobs it into the portal. It is compatible, much to Zim's surprise. The pig replaces Dib's tricycle in the past, causing it to crash. In the present, Dib gets road rash scars on his face and a metal claw for a hand.
Zim decides to use the rubber pigs to screw with Dib's life some more. His next chance comes when Dib borrowed his dad's hover helmet. When he's in the sky, Zim replaces the helmet with a pig, causing Dib to fall. In the present, Dib gains tubes in his neck, connecting to a breathing apparatus on his back, as well as visions of pigs in his head.
The third pig accident causes Dib to fall off a tower while investigating a bigfoot baby. In the present, he ends up in even worse shape. He goes over to Zim's house, and when he sees a rubber pig that GIR drops, he bangs on the door, accusing Zim of being behind the accidents. Another accident replaces defibrillator panels with rubber pigs, and, on a screen in Zim's base, Dib's vitals flatline.
A triumphant Zim gets a soda and leaves his base. Because he's not there, he doesn't notice Dib's history, heartbeat, and lifeline restart. The screen in the past shows Professor Membrane at a press conference, announcing the Mega Boy 3000 titanium exoskeleton he created for Dib. In the present, Zim emerges from his base to find the house shaking, with Dib yelling that he will pay for ruining his life. Dib breaks through the wall of Zim's house, with the laser defenses having absolutely no effect.
In his base, Zim desperately throws rubber pigs into the portal, hoping that at least one of them will reach a point in Dib's history where he was still vulnerable. Unfortunately, this just leads to the Mega Boy being upgraded, mostly with new weaponry. As Dib assaults the base, GIR offers one last rubber piggy to Zim, who realizes that he does have one last chance to stop this- he'll need to warn his past self not to use the time machine.
Zim throws the last piggy into the portal just in time. Dib reverts to his normal state, outside the house. He's got a bit of jamais vu, but is otherwise all right. Zim himself, however, not so much- the object the pig replaced in the past was his past self's brain.
Tropes
- Aliens Speaking English: Zim's handwritten message on the final piggy is written in English, despite previous episodes showing that the Irkens have their own alphabet.
- Artificial Limb: Thanks to one of the accidents Zim causes in his past, Dib ends up having a mechanical claw for a hand.
- Brain Theft: Zim accidentally does this to himself by replacing his past self's brain with the rubber piggy he intended to use to warn him not to use the machine.
- Brick Joke: One of Professor Membrane's examples against making a Spacetime Object Replacement Device is a rampaging giant fish in a bear suit. Illogical as it may sound, when Zim first discovers how he can use the piggies to kill Dib, it then cuts to the news, reporting that giant fish people are attacking Tokyo, with one wearing a bear suit and holding a picket sign saying, "Hi, Mom!".
- Butterfly of Doom:
- Discussed by Prof. Membrane; he explains (using the creation of a breakfast cereal for example) that preventing or altering an event would cause more problems than doing so would solve.
- It's too bad that Zim didn't see this, as his plan in this episode invokes the Butterfly of Doom all over the place. His attacks on Dib lead to Dib's death, but then to Dib being put in the Mega Boy and being utterly furious with Zim for ruining his life. A later attack ends up giving the Mega Boy missiles.
- Caught in the Ripple: Every alteration Zim makes in the past radically changes Dib’s future. He always notices something is off when a dramatic change happens, but then realizes, no, he’s always had that memory. This is also reinforced by Gaz reminding him of each past accident.
- Department of Redundancy Department: "You can hide, Zim, but you can't... hide!"
- The Dog Bites Back: After spending the bulk of the episode suffering pig-related accidents, Dib goes on a Roaring Rampage of Revenge against Zim using his new Mega Boy exoskeleton suit.
- Doomy Dooms of Doom: "Now, to unleash screaming temporal doom!"
- Exactly What It Says on the Tin: Zim creates a robot that will hunt down and kill Dib in the past, and calls it... a Hunter Destroyer Machine.
- Everyone Has Standards: While the rest of the show depicts the masses are generally apathetic and stupid, the crowd around Dib as he's being defibrillated are visibly disturbed and upset at the possibility that a little boy might die.
- Gone Horribly Right: Zim's attempts to kill Dib do indeed work. It's what happens after that's the problem.
- Gone Horribly Wrong:
- Zim's plan ends up rendering Dib ten thousand times as strong, immune to all Zim's defenses, and bent on revenge against Zim, with any further attempts just making him stronger. Zim has to erase the plan from history in order to survive.
- And his plan to erase his original plan from history ends up rendering Zim into a mindless husk when the pig with the message ends up replacing his own brain.
- Kindness Ball: After Zim starts targeting Dib in the past and messing him up in the present, Gaz seems much more patient and kind to Dib than she normally is. She calmly explains to Dib the accidents that happened to him that caused his disabilities and almost sounds concerned for him when he doesn't remember them right away.
- Laser-Guided Karma: Zim gets his brain replaced by a rubber piggy, rendering him a drooling husk.
- Logic Bomb: GIR does this to himself by pointing out how Zim is invoking the Grandfather Paradox. It literally makes his head explode.GIR: Wait... if you destroy Dib in the past, then he won't ever be your enemy. Then you won't have to send a robot back to destroy him, and then he... will be your enemy, so then you will have to send a robot back... (kaboom)
- Make Wrong What Once Went Right: Zim's plan is to kill Dib in the past. He first tries a giant robot, then the rubber pigs, which end up causing accidents to happen to Dib. It works and does briefly end up killing Dib- until Professor Membrane resuscitates him...
- Man in the Machine: Dib is turned into one as a result of Zim's attempts to retroactively assassinate him.
- Near-Villain Victory: Zim comes close to outright killing Dib, but is thwarted once Professor Membrane creates the Mega Boy exoskeleton for his son, allowing Dib to take revenge on Zim by trashing his entire base. Dib himself gets a "near Hero Antagonist victory" before Zim manages to hit the Reset Button.
- No-Sell: The Mega Boy is immune to all of Zim's defenses, and takes apart the base with ease.
- Papa Wolf: When Zim seemingly kills Dib when he is just a child, Professor Membrane manages to not only revive his son but improves him by building an exoskeleton suit for him that increases his strength ten thousand fold. All of Zim's attempts to kill Dib in the past after this only result in the suit getting stronger, implying that Membrane continued to upgrade the suit in order to save Dib each time he was endangered.
- Pet the Dog: Zim initially wants to keep all of GIR's rubber piggies to himself For Science!, but lets him keep one when he sees GIR crying.
- Reactive Continuous Scream: A brief one happens between Dib and Gir when the former walks by.
- Roaring Rampage of Revenge: Once Dib realizes that Zim has been responsible for the rubber piggies that have ruined his life, he attacks Zim with his new suit with the intent to outright kill him and GIR.
- Set Right What Once Went Wrong: How the plot is eventually solved- Zim sends a note to his past self warning him not to use the time machine. The note ends up replacing his brain instead of being read by him, but the end result is still a Dib who's not a furious vengeful cyborg.
- Shout-Out: Zim originally intended to use the time machine to send a robot into the past to kill his mortal enemy ala The Terminator.
- Space Whale Aesop: According to Professor Membrane, don't build a Spacetime Object Replacement Device, or else a giant fish in bear suits will destroy cities.
- Spanner in the Works: Professor Membrane singlehandedly causes Zim's plan to Make Wrong What Once Went Right to crash and burn by putting Dib in the Mega Boy suit.
- Super-Powered Robot Meter Maids: Professor Membrane's efforts to revive his son involve putting the boy in a mecha suit that gives him ten thousand times his strength. He later gives the robot missiles. Though given that this is Professor Membrane we're talking about, we're pretty lucky that was all he gave it.
- Take That!: Breakfast Chunks are based on the equally-unpopular Kellogs Breakfast Bars.
- Unexplained Recovery: Happens to GIR after he logic bombs himself.
- Who Would Be Stupid Enough?: Indirectly, but Membrane, during his show, declares that anyone who would build a spacetime object replacement device would have to be an absolute moron. Just such a device is Zim's Dib-murder tool of the episode. Zim's escapades with his portal basically prove Membrane right, as the Butterfly of Doom causes Zim to nearly die.
- Xanatos Speed Chess: Initially, Zim intended to send a hunter destroyer robot into the past to kill Dib, only for it to be rejected by the machine because it wasn't compatible with the temporal field. However, upon discovering that Gir's rubber pigs could be sent into the past, Zim decided to improvise by sending them to various moments in Dib's past to cause him increasingly violent accidents.
- You Can Run, but You Can't Hide: Inverted, by way of Dib screwing up the order of the sentence (granted, by this point he's probably suffered a lot of brain damage)."YOU CAN HIDE, ZIM, BUT YOU CAN'T..."
(Beat as he realizes his mistake before rolling with it)
"...HIDE!" - Your Head Asplode: Happens to GIR as a result of his self-inflicted Logic Bomb.
- ZIM, don't use the time machine! Love, ZIIIIIIIIIM!
